This application claims priority under 35 U.S.C. 371 from PCT International Application No. PCT/EP97/05517. filed on Oct. 8, 1997, which in turn is based on EP application 96202823.1 filed on Oct. 9, 1996.
This invention is related to compositions encapsulating food additives and to methods for forming the compositions.
The present invention relates to a process for preparing beads as food additives containing at least one active ingredient, to a method of use of the beads and to the beads themselves.
A frequent problem associated with the application of flavor systems is the loss of flavor by volatilization or chemical decomposition. The harsh environment of some food processes like baking, extruding, retorting and deep frying, to name a few, create unique problems for the survival of flavors in finished food products. The loss of flavor usually results in flavor profile distortion or even in complete loss of flavor. Therefore, food scientists and application specialists are continuously searching for methods to protect flavors against volatilization and decomposition during processing.
Another category of flavor application problems results from differences in the interaction between the flavor compounds and the product base. These differences in the flavor-matrix interactions result also in flavor distortion due to the different rates of flavor release during consumption of the product. Typical examples of this type of flavor application problems are the change of flavor character and strength in chewing gum during mastication and the flavor imbalance observed when applying standard flavors to low fat products.
One of the preferred methods to control flavor retention and release is encapsulation. A considerable amount of effort has been devoted for many years to provide solid particulate flavoring materials in which a flavor is contained in the particulate matrix. Various attempts have been made to fix the flavors in many different types of organic matrices to provide stable free-flowing powders of particles which contain the flavor for flavor release when incorporated in foods.
Several principle technologies have been proposed for the preparation of solid particulate flavoring materials.
The first category of encapsulated flavors consists of water-soluble particles containing a dispersion of flavor oil. A number of water-soluble carrier materials are employed in the production of this type of encapsulated flavors, such as sugars, modified starches and gums. The industry commonly utilizes spray drying, extrusion and fluidized bed coating to produce the particles. Flavors encapsulated in a water-soluble matrix can be used for controlling flavor delivery and improving flavor stability in dry products such as chewing gum, pressed tablets and dry mixes for the preparation of instant soups, beverages, sauces and desserts. However, this type of encapsulation is unsuitable for improving flavor performance in products that contain water because of dissolution of particulate flavoring materials. Since in the preparation of most foods, water is involved at any stage of the processing, encapsulation in water-soluble matrices has limited applicability for improving flavor stability or for controlling flavor retention and release.
To overcome the problem of dissolution of the capsule matrix during processing in moist environment, fat encapsulation is sometimes being used (second category). However, the use of fat encapsulated flavors is limited to food products that are processed at relatively low temperatures, because at temperatures above the melting point of the fat much of the effectiveness of the encapsulation is lost. In practice, this means that fat encapsulation cannot effectively be used for controlled flavor delivery in products that are heated above 80xc2x0 C. which comprises the majority of products that are boiled, baked, roasted, (deep) fried or extruded.
The third category of encapsulated flavors consists of particles that are water insoluble and heat stable. The methods currently being used to prepare such particles are micro-encapsulation by coacervation and encapsulation in microorganisms.
The encapsulation of flavor oils in heat-stable water-insoluble coacervation microcapsules is described in the patent applications WO 93/19621 and WO 93/19622. Micro-encapsulation by coacervation creates a barrier of protein around a droplet of flavor oil. This barrier provides improved flavor retention during heat processing and higher shelf-life stability. Moreover, it can provide improved flavor performance through enhanced flavor release during consumption as, for example, in chewing gum. The coacervation microparticles release-the flavor by fracturing the protein membrane surrounding the flavor oil during mastication. For optimum results, it is important that the capsules are engineered for high flavor retention during processing without adversely affecting flavor release.
The encapsulation of flavor oils in microorganisms is described in European patent application 242,135. This method of encapsulation provides particles, each consisting of a droplet of oil surrounded by a double layer consisting of a cell membrane and a capsule wall. The application of microbial cells for enhanced flavor release from chewing gum has been described in European patent application 528 466. The results of the organoleptic evaluations indicate that the flavor release is by fracturing. In this and other respects, the behavior of microbial cells resembles that of coacervation microcapsules.
Both microbial cells and coacervation microcapsules are able to survive food processes like baking, extruding, retorting and deep frying. The major risk for this type of capsules is that they are ruptured during the process as a consequence of the shear forces applied during mixing, grinding or other high-shear processes to which the product is subjected during its production.
Other potentially interesting materials for the preparation of heat stable, water-insoluble flavor microparticles are salts of anionic polysaccharides such as the calcium salts of alginic acid, pectin and gellan gum. Calcium alginate, in particular, has found useful application as a water insoluble matrix for the encapsulation of microbial cells (T. Shiotani and T. Yamane, Eur. J. Appl. Microbiol. Biotechnol. 13 (2) 96-101 [1981], H. C. Provost, Divies and T. Rousseau, Biotechnol. Lett. 7 (4) 247-52 [1985]), enzymes (P. Brodelius and K. Mosbach, Adv. Appl. Microbiol. 28, 1 [1982]), drugs (H. Tomida, C. Mizuo, C. Nakamura and S. Kiryu, Chem. Pharm. Bull. 41(12) 2161-2165 [1993]), vitamins (U.S. Pat. No. 4,389,419), colorings (K. Saito, T. Mori and K.-I. Miyamoto, Food Chem. 50, 311-312 [1994]), and herbicides (A. B. Pepperman, J. C. W. Kuan and C. McCombs, J. Controlled Release 17, 105 [1991]). However, for the encapsulation of flavors, calcium alginate or other heat stable polysaccharides have hardly been used. This is not surprising in view of the poor barrier properties of these gels for flavor compounds.
The use of alginate for controlled flavor delivery is described in European patent application 221,850. According to this, encapsulation in calcium alginate is used for controlled delivery of water-insoluble flavors from chewing gum. The process for encapsulation involves separation of the alginate matrix from a large excess of water followed by air drying. Therefore, this process is not suitable for encapsulation of water-soluble and volatile flavors, because these compounds either remain in the aqueous phase or volatilize during drying. Moreover, the approach does not allow control of flavor release by variation of particle size, porosity and flavor solvent composition.
A While the above methods for the preparation of heat-stable, water-insoluble capsules allow improvement of flavor retention under harsh conditions, there are a few restrictions that limit a wider application of these technologies. For example, with the above methods, flavors of high volatility and water-solubility cannot be encapsulated or encapsulated only with poor efficiency. Moreover, most particles consisting of a core surrounded by a shell of capsule material cannot withstand high shear conditions with the consequent risk of premature release by capsule breakage.
In the copending European patent application number 96 20 2822 the production and use of flavors and other active ingredient(s) encapsulated in moist alginate beads that meet some the above demands have been described. Although the method gives good results with poorly volatile and water insoluble flavors, the encapsulation efficiency is often poor with water soluble and volatile flavor compounds. Therefore, it would be advantageous to have an alternative method of flavor and other active ingredient(s) encapsulation that allows encapsulation of water soluble and/or (very) volatile flavor and/or other active ingredient(s) constituents at high efficiency and that shows similar or even better performance in the application. An object of the present invention is to fulfill this demand.
The demand is fulfilled by beads consisting of a matrix of a reticulated multivalent cation containing acid polysaccharide and at least one water soluble and/or volatile liquid active ingredient and/or one water soluble and/or volatile solid active ingredient filling at least partly the voids built by the acid polysaccharide. The active ingredient is at least one compound of the group consisting of flavors, fragrances, vitamins or coloring materials. Especially the active ingredient is a liquid or solid flavor, in particular a flavor oil, or a flavor dissolved in oil. Said multivalent cation containing acid polysaccharide may preferably be an alginate, especially calcium alginate. Said acid polysaccharide may be a pectin, especially a low ester pectin, preferably with a degree of esterification of less than 5% by weight. The acid poolysaccharide may also be gellan gum. The beads are heat stable and the active ingredient is being sustainedly released. Further, the beads are mechanically stable and have a diameter of about 10 to about 5000 xcexcm, preferably 100-1500 xcexcm, most preferably 400-1200 xcexcm.
The beads can be prepared by the following process:
A process for preparing beads as food additives containing at least one water soluble and/or volatile active ingredient which is released at a controlled rate. The process forms a system of a dispersion or emulsion of a water immiscible mater in an aqueous solution of an acid polysaccharide, especially in the form of an alkali metal salt, an emulsifier, and optionally one or more other water soluble or water dispersible substances. Discrete droplets of the system are then formed. The droplets are converted to water-insoluble gel beads by introducing the droplets in an aqueous or alcoholic solution containing multivalent cations, thereby building a suspension of gel beads. The gel beads are isolated from the suspension and the isolated beads may optionally be dried. The isolated beads are loaded with at least one active ingredient which may be one or more flavor, fragrance, vitamin, and/or coloring materials.
In the process the water immiscible material is a lipid, in particular a vegetable oil, a fat, a mono- or diglyceride, or a lipophilic fat replacer, especially a sucrose polyester. Said acid polysaccharide in the form of an alkali metal salt is preferably as an alginate, especially sodium alginate. Said acid polysaccharide may be a pectin, especially a low ester pectin, preferably one having a degree of esterification of less than 5% by weight. The acid polysaccharide may also be gellan gum. The emulsifier may be a modified starch, especially an octenyl succinated starch. The water-soluble substance may be a polysaccharide, preferably the polysaccharide is at least one of the group consisting of maltodextrin, modified cellulose, especially methyl or ethyl cellulose, locust bean gum, dextran, gum arabic and konjac. A protein as the water-soluble substance is also preferred. The water-dispersible substance may be an adsorbent, especially silicon dioxide. The multivalent ions may be ions from the group consisting of calcium, strontium, barium, iron, silver, aluminium, manganese, copper and zinc, especially calcium ions.
Said forming of discrete droplets may be generated by a spraying method known per se, especially by pouring the system on a rotating disk, or by extruding or pumping said system through an orifice or a needle at a rate slow enough to prevent the formation of a jet, or by building a jet of said system and breaking up said jet by means of a resonance technique known per se, e.g. vibration or pulsation.
The beads may be isolated from the suspension by filtration or centrifugation, thereby yielding moist beads, which beads may be dried, especially in an oven or fluid bed dryer. Preferably the moist beads are dried in the presence of an anti-caking agent, especially in the presence of starch, maltodextrine or silicon dioxide. Said loading of the moist or dry beads with at least one active ingredient is advantageously performed by contacting the active ingredient(s) with the moist beads at room or elevated temperature and allowing the active ingrdient(s) to be absorbed or adsorbed into the beads.
The beads according to the invention which are preferably prepared by the afore described process can be used in a method for flavoring, perfuming, vitaminizing or coloring food which comprises adding the beads to the food in an effective amount, whereby the addition of the beads to the food can be performed prior to or during an extruding step of the food product or by coating the food with said beads or even prior to drying, frying, baking, cooking or boiling the food because of their mechanically stability. Adding flavor containing beads to no- or low-fat dry mixes which are used for the production of flour-based food are of specific interest and therefore this method is one of the preferred ones. Further preferred is the addition of the beads to a low fat version of a regular food product.
The invention is now further described in detail.
The present invention provides a method for encapsulating water soluble and/or volatile flavors, vitamins, coloring materials and other active ingredients into a water insoluble, heat stable polysaccharide matrix in such way that the performance of the encapsulated ingredient in the application is improved by reducing the risk of flavor loss by volatilization or chemical decomposition during (heat) processing, and or by enhancing or modifying the flavor release during consumption of the food. The method allows encapsulation of water soluble and highly volatile flavor ingredients, such as acetoin and diacetyl, at high efficiency.
The invention is directed to a method for encapsulating flavors and/or also other active ingredients in microparticles for optimum active ingredient performance in foods. More particularly, it is directed to a method of producing edible microparticles comprising a matrix of essentially water-insoluble shape-retaining alginate gel held together by salt bridges. In the preferred embodiment of the invention, the process consists of the following steps:
production of a suspension or slurry of gel particles, in particular, gel beads, consisting of a multivalent cation containing acid polysaccharide and containing a water-insoluble flavor solvent,
isolation of the gel beads from the slurry by filtration or centrifugation,
optionally, dehydration by oven or fluid bed drying, and
absorption of the flavor into the gel beads.
In this application beads are defined as solid particles with a homogeneous composition and texture from inside to outside in which the flavor droplets or particles are uniformly distributed. Capsules, on the other hand, are defined as particles consisting of a liquid or solid core of the active ingredient surrounded by a shell.
The dry encapsulation process according to the invention overcomes the difficulties encountered in the encapsulation of water-soluble flavors when using the above described wet slurry technologies of coacervation and absorption into microorganisms.
Flavor microparticles produced according to the invention substantially retain their structural integrity in food processes thus allowing effective protection of the flavor ingredients against volatilization and decomposition. If the active ingredient is a flavor, the flavor microparticles provide sustained release of the flavor to the finished product during storage and prior to consumption. The invention accordingly provides a inexpensive method to enhance flavor effectiveness by preventing flavor loss and/or enhancing flavor release.
The production of the flavor microparticles starts with the preparation of an emulsion consisting of a dispersed oil phase in an aqueous solution of an alkali metal alginate. The oil phase may consist of a vegetable oil, a molten fat or any other lipid material that has good flavor solvent properties and is suitable for human ingestion. Optionally, an emulsifier and an extender or filler material may be added. Non-volatile, poorly water-soluble flavor ingredients may also be added at this stage.
Subsequently, the emulsion is dripped or sprayed into an aqueous or alcoholic solution of multivalent cations which are preferably calcium ions, to convert the droplets into shape retaining, water-insoluble gel microparticles. The gel particles are isolated from the resulting suspension or slurry of gel beads by filtration or centrifugation. The resulting moist flavor microparticles may be mixed with an anti-caking agent to obtain a free flowing product. Optionally, this product may be further dried at atmospheric or reduced pressure to obtain a product with a minimum amount of residual water and/or alcohol. The microparticles thus produced are mechanically stable.
The dried xe2x80x9cblankxe2x80x9d gel beads are loaded with flavor by mixing the flavor with the beads. The flavor is allowed to be absorbed or adsorbed as into the beads which might take a few days. This results in a uniform distribution of the flavor over the beads. The major part of the equilibration may also take place in a package. To accelerate the absorption of flavor compounds into beads, in particular those containing solid fat, the beads may be equilibrated at elevated temperature.
The present invention provides a cost-effective process for the efficient encapsulation of volatile and water-soluble flavors. The process allows encapsulation of flavorings of different consistency, water-solubility and volatility. Further, the process allows manipulation of flavor retention and release by use of filler materials, adsorbents or flavor solvents with different melting points. Also, the present invention provides a process for preparing colored particles by the addition of a coloring material to the above process.
The present invention provides micro-beads with a unique combination of desirable properties. The particles may have different shapes varying from beads to fibers and can contain different concentrations of flavor oils and/or solid flavor materials, varying from less than 1 to more than 80% by weight. The microparticles of this invention can much better withstand the harsh conditions during food processing than any other microcapsules currently being used for flavor encapsulation. For example, the gel beads are heat and freeze stable both in dry and moist environments. Moreover, they can withstand high shear conditions. For all these reasons, the micro-beads are particularly suited for use in products that are subjected to high shear and heat stress during their production.
In the preferred embodiment of the invention, an alkali metal alginate, preferably sodium alginate, is dissolved in water to produce a solution containing between about 1 and 5% by weight of the alginate. All hereafter mentioned percent values are percent values by weight. Concentrations of alginate below about 0.5% are increasingly ineffective in producing defect-free micro-capsules. Alginate concentrations above 4%, although desirable for reasons of encapsulation effectiveness, are often too viscous to allow formation of small beads of uniform size. Instead of an alkali metal alginate, pectin or gellan gum may also be used in this process.
Alginates are linear copolymers of a-L-guluronate (G) and b-D-mannuronate (M). The alginate chain may be regarded as a block copolymer consisting of xe2x80x9cG-blocksxe2x80x9d (homopolymeric regions of guluronate residues,) xe2x80x9cM-blocksxe2x80x9d (homopolymeric regions of mannuronate residues) and xe2x80x9cMG-blocksxe2x80x9d (copolymeric regions of a random-like alternating sequence of M and G) of varying length. Besides being heterogeneous with respect to the chemical composition, alginates have quite a broad molecular weight distribution. Alginate is a collective term for a family of polymers. Their properties depend on their block structure and molecular mass.
Above a certain critical molecular mass the properties of the alginates are mainly governed by the monomeric composition and block structure. In general, an increase in the content of guluronate gives mechanically stronger gels with enhanced stability in the presence of non-gelling/anti-gelling ions (e.g. Na+, Mg2+) and calcium sequestering agents. High guluronate containing gels exhibit high porosity and low shrinkage during gel formation. At high content of mannuronate, the gels become softer and more elastic; they shrink more during gel formation with concomitant reduction of porosity. For encapsulation of flavors, all types of alginate can be used but those with a molecular weight are generally preferred because it turned out that they are more effective because of their high mechanical stability.
Instead of sodium alginate, the structurally related pectin may be used for the production of water insoluble, heat stable gel beads. Pectin is a hydrocolloid consisting of polygalacturonic acid of which the carboxylic acid groups are partly esterified with methanol. For high heat stability, the use of a pectin with a low degree of esterification, especially less than 5%, is preferred.
Gellan gum is a high-molecular-weight heteropolysaccharide consisting of a linear tetrasaccharide repeat structure comprising 1,3-xcex2-D-glucose, 1,4-xcex2-D-glucuronic acid, 1,4-xcex2-D-glucose and 1,4-xcex1-L-rhamnose. It forms gels with several counter ions of which the divalent ions, such as calcium and magnesium, give maximum gel hardness. Gels formed in the presence of calcium ion concentrations higher than 10 mM are heat stable under normal food processing conditions.
The relatively large pore size of the heat stable polysaccharide gel beads restricts the capability of alginate gels to act as an insurmountable barrier for small molecules, such as flavor molecules, vitamins, etc. Nevertheless, an alginate gel may sustain the release of molecules to a different extent depending on the barriers within the gel. If for example, the gel contains other (macro)molecules, the effective porosity will decrease and the sustained release will be at a lower rate. For this reason, it is sometimes advantageous to add a filler material such as native starch or silicon dioxide to the alginate solution. Other suitable filler materials include polysaccharides such as dextrins, dextran, locust bean gum, gum arabic and methyl cellulose, ethyl cellulose, hydroxypropyl cellulose and proteins, such as gelatine.
In addition to filler materials, emulsifiers such as octenyl succinated starch and mono- and diglycerides, or mixtures of mono- and diglycerides, may be added to the aqueous solution of the acid polysaccharide. These emulsifiers help to obtain an oil-in-water emulsion of high stability which is a prerequisite for the formation of beads of constant composition and size.
Next, vegetable oil, fat or any other suitable water-insoluble flavor solvent to be incorporated into the micro-beads is added to the aqueous solution, typically in the range of about 2-25%. Among the water-insoluble flavor solvents useful in the practice of the invention are vegetable oils, solid fats of different melting point and mono- or diglycerides. For application in low- and no-fat products, a lipophilic fat replacer, for example, a sucrose polyester such as Olestra(copyright) (Procter and Gamble), may be used. At this stage, also water-insoluble flavor carriers like silicon dioxide may be added as well as coloring materials and non-volatile flavor ingredients, such as aspartame or capsaicin.
The resulting two phase system is subjected to rapid stirring to induce emulsification of the oil phase in the aqueous phase. A homogenizer or another high shear mixing apparatus is useful for this step. Preferably, the resulting particle or oil droplet size in the emulsion is in the 1-10 micrometer range to ensure good stability of the suspension or emulsion during at least the period of bead formation (up to a few hours). After formation of the emulsion, the gel particles are prepared using one of the following methods.
One of the preferred methods of gel bead production consists of generating droplets by spraying using a nozzle or disk and collecting the droplets, while substantially spherical, in a multivalent cation containing solution, e.g., an aqueous or alcoholic solution of calcium chloride. The droplets are of a size preferably within the range of about 100-5000 micrometers. As the droplets enter the solution, the alkali metal counter-ions of the acid polysaccharide are exchanged by calcium ions, resulting in instantaneous gelation of the droplets through the formation of multiple salt bridges between the acid polysaccharide molecules.
Another method of droplet generation consists of extruding or pumping the emulsion through a needle or orifice at a speed slow enough to prevent the formation of a jet. This method provides beads of very uniform size but the production capacity is low. Much higher capacity is achieved by making use of a resonance technique which consists of breaking up a jet of the emulsion into uniform droplets by means of a resonanation (A. C. Hulst, J. Tramper, K. van""t Riet and J. M. M. Westerbeek, Biotechnol. Bioeng. 27, 870-876 [19851]). Therefore, the latter method is preferred for the large-scale industrial production of the gel beads.
Still another method for the production of polysaccharide gel microparticles consists of preparing a gel using mixtures consisting of a sodium salt of an acid polysaccharide and one other gel forming polymer such as agar, and to break the gel into small particles by shear. Subsequently, a concentrated solution of calcium chloride is added to convert the water soluble salt of the acid polysaccharide into an insoluble calcium salt in order to obtain microparticles of high heat stability. The particles obtained by this method have an irregular shape which might be an advantage in some applications. In principle, particles of any shape can be used for the flavor encapsulation provided that the dimensions are not that extreme that the flavor retention and release are adversely affected.
Calcium ions in the concentration range of 1-10% are the preferred multivalent cations for alginate gelation because of their high effectiveness, low costs and low toxicity. In principle, other metal ions such as strontium, barium, iron, silver, aluminum, manganese, copper or zinc ions may also be used. When the calcium chloride meets the drops of the acid polysaccharide, a skin of insoluble calcium alginate forms at once on the outside. Thereafter, calcium ions diffuse slowly into the drops and so a reasonable time is necessary for full conversion to solid gelled particles. For drops of a diameter of 100-5000 micrometers, and a calcium chloride solution of 1-5%, the contact time should be from 1 to 500 minutes.
When calcium ions diffuse into the solution of the acid polysaccharide, the rapid ion-binding and network formation produces an inwardly moving gelling zone. The acid polysaccharide itself will also diffuse towards this gelling zone, leading to a depletion of polysaccharide in the center. A gel bead with such an inhomogeneous distribution of alginate may be advantageous for certain flavor applications because of the higher gel strength in the outer zone. In fact, in this way capsules may be formed consisting of an alginate shell around a droplet of flavor oil. In general, low molecular mass alginate, low concentration of gelling ions and absence of non-gelling ions give the highest inhomogeneity, whereas a high molecular weight polysaccharide, and a high concentration of non-gelling ions all give increased homogeneity.
The preferred solvents for the solution of multivalent cations are water and/or a low molecular weight alcohol such as methanol, ethanol and isopropyl alcohol. Higher molecular weight alcohols may also be used, but the low molecular weight alcohols are preferred because they can be removed more easily from the micro-beads by volatilzation. In general water is the preferred solvent. However, if a water soluble filler material is being used, alcohol is the preferred solvent because it precipitates the water-soluble filler within the gel matrix.
The microparticles prepared by one of the above methods can be isolated from the slurry by filtration or centrifugation. Optionally, they are washed with water, alcohol or a mixture of water and alcohol to remove adhering sodium and calcium salts. To obtain a free flowing product, starch, silicon dioxide (e.g. Syloid(copyright)), maltodextrin or any other water binding material can be added after isolation. Since different combinations of flavor (solvent) and acid polysaccharide cause different shrinkage during drying, the volume of flavor oil in the original emulsion should be optimized for different polysaccharides in order to obtain dry particles with little surface oil and a minimum tendency to stick together.
The water insoluble gel particles, consisting of a porous gel network containing entrapped flavor solvent, are loaded with flavor by mixing the liquid flavor with the particles while tumbling over in a blender or dryer. If the particles contain solid fat, it might be advantageous to use slightly elevated temperature to enhance the rate of flavor diffusion into the particles. When most of the flavor has been absorbed by the particles and the particles no longer have a strong tendency to stick together, they are transferred into bottles or drums where they are allowed to equilibrate for a few days to achieve uniform distribution of the flavor over the beads by migration. If the beads remain sticky, additional starch or other anti-caking agent is added to obtaining a free flowing product.
A variety of flavors and flavor ingredients may be encapsulated in the gel microparticles. These flavors include flavor compounds, and complex mixtures like extracts, essential oils, oleoresins or reconstituted natural, nature-identical or artificial flavors. Natural extracts, essential oils and oleoresins include fruit essences, vanilla extract, capsicum oleoresin, pepper oleoresin, cinnamon oil, oil of winter green, peppermint oil, bay oil, thyme oil, spearmint oil, cassia oil, citrus oils, and the like. Reconstituted natural, nature-identical and artificial flavors include apple, cherry, strawberry, peach as well as meat, cheese, tomato and butter flavors. These flavorings may be used individually or in a mixture as is well known in the art.
The heat-stable, sustained-release polysaccharide gel beads as obtained by the processes according to the invention may be employed to improve flavor impact in a wide variety of food applications. For instance, encapsulation in a multivalent cation containing acid polysaccharide matrix may be used to protect the flavor against volatilization and chemical decomposition during heat processing. The term heat-stable as used herein means protected against deteriorating effects of heat under dry and/or moist conditions. The heat-stable polysaccharide microparticles are particularly suited for improving flavor retention in solid or semi-solid foods during microwave heating, boiling, cooking, baking, frying, roasting, drying, and extrusion. Moreover, they are able to protect flavors in liquid products like soups and sauces against chemical decomposition or volatilization during retorting, boiling, pasteurization or sterilization.
Dried gel microparticles are preferred for use in products that require heat processing to produce the finished product. In such applications, the performance of dry microparticles is much superior to the performance of wet microparticles such as slurries and filtered beads (moisture content more than 50%), and slightly superior to microparticles isolated by centrifugation (moisture content of starch coated beads 15-20%). A Study of the relationship between flavor loss during heat processing and the steam volatility of the flavor constituents strongly suggests that steam distillation from the microenvironment of the moist flavor beads is the major cause of the flavor losses from moist gel particles. Since dry calcium alginate does not easily rehydrate, a low moisture microenvironment is maintained around the flavor during the initial period of the heat processing, thus resulting in the superior performance of the dry alginate beads as compared to the wet beads.
One of the major advantages of use of flavor encapsulation in water insoluble polysaccharide microparticles is that the encapsulation does not adversely effect flavor release during consumption. One of the reasons for this is that the microparticles provide sustained release of the flavor to the product during storage and prior to consumption. Another reason is that the flavor release from the beads is as, good as or even better than, the release from the food matrix in which the unencapsulated flavor constituents are entrapped. The release can be influenced by varying the flavor solvent, the filler materials, the type of acid polysaccharide used and the conditions used for formation of the alginate gel particles. For example, the time-intensity profile of flavor release can be influenced by varying the conditions of the gelation with calcium, e.g., by changing the calcium ion concentrations or the duration of gel formation. Because of their ability to influence flavor release, the alginate microparticles are also particularly suited for use in chewing gum and low fat products such as low fat ice cream.
A well known problem with chewing gum is the large difference in the interaction between flavor compounds and the gum base which results in very different rates of flavor release. This might result in undesirable changes during chewing. Moreover, the strong retention of most flavor compounds by the gum base results in a very slow level of flavor release and flavor perception in spite of the high flavor concentrations present in the gum base. Flavor encapsulation in water insoluble gel particles provides improved flavor release from chewing during mastication. Both the flavor impact (strength and character) and the time-intensity profile of the flavor release may be influenced by proper choice of flavor solvent, alginate type and filler materials.
Because of their ability to influence flavor release, the water insoluble polysaccharide gel particles are also particularly suited for use in low fat products such as low fat ice cream. An example of poor taste perception in low fat products is vanilla ice cream. The reduction of the fat content in ice cream results in distortion of the vanilla flavor profile due to the effect of the fat on flavor release. Moreover, it results in poor flavor stability (U.S. Pat. No. 5,536,519). Encapsulation in a water insoluble, fat or oil containing polysaccharide matrix helps to improve flavor performance by the creation of a microenvironment surrounding the flavor that mimics the original full fat base. Best results are obtained with flavor solvents that are solid at low temperature but fluid at the temperature in the mouth during the consumption of the ice cream. The advantage of encapsulation in a polysaccharide matrix over fat encapsulation is that free flowing flavor microparticles can be prepared from oils or fats of low melting point without the need of low temperature storage.